The present invention relates to a resist composition suitable for lithography and the like, which acts by high energy radioactive ray such as far ultraviolet ray (including excimer laser and the like), electron beam, X ray or radiation light.
Recently, according to high integration of integrated circuits, submicron pattern formation is required. Particularly, lithography using a radiation source such as excimer laser light from krypton fluoride (KrF), argon fluoride (ArF) and fluorine (F2), electron beams EUV light, X ray and the like is noticed since they enable fine pattern formation. As the resist suitable for a lithography process, a so-called chemical amplifying type resist utilizing an acid catalyst and chemical amplifying effect is adopted. In the chemical amplifying type resist, acids generated from an acid generating agent at a part irradiated with radiation are diffused by the subsequent heat treatment (post exposure bake; hereinafter, abbreviated as PEB in some cases), and the solubility of the irradiated part in an alkali developer is changed by a reaction using this acid as a catalyst. Thus, a positive or negative pattern is given.
In positive resists of chemical amplifying type, resins in which an alkali-soluble group is protected by a group which is dissociatable by the action of an acid are often used in combination with an acid generating agent. It is reported that high resolution and excellent dry etching resistance are obtained particularly by using a protective group such as a 2-alkyl-2-adamantyl group or 1-adamantyl-1-alkylalkyl group as shown in S. Takechi et al., J. Photopolym. Sci. Technol., Vol. 9, No. 3, 475-487 (1996) and JP-A-9-73173, as the group dissociatable by the action of an acid as described above. Nozaki et al., J. Photopolym. Sci. Technol., Vol. 13, No. 3, 397-403 (2000) discloses a resist for electron beam using a copolymer resin of 2-methyl-2-adamantyl methacrylate or 2-ethyl-2-adamentyl methacrylate with hydroxystyrene, and reports that particularly those using a copolymer resin of 2-ethyl-2-adamantyl methacrylate with hydroxystyrene have high sensitivity and are excellent in etching resistance, and provide high resolution in exposure to KrF excimer laser.
However, chemical amplifying type positive resists using a copolymer of 2-ethyl-2-adamantyl methacrylate with hydroxystyrene have a problem of generation of scum after development.
An object of the present invention is to provide a chemical amplifying type positive resist composition having excellent sensitivity and resolution and showing less scum problem.
The present inventors have intensively studied for attaining such objects. Resultantly, they have found that excellent performances can be obtained without generation of scum by using a specific copolymer as a resin component of a chemical amplifying type positive resist and allowing polypropylene glycol to be contained in the resist. Thus, the present invention was completed.